Oracle Pl/SQL procedure to update values of one table to another

Question

My requirment here is i have two tables with two attributes.I have written a procedure which should take values(sor_ID) from table1 and update it in Table 2 based on primary key.

Table 1 
-------
Primary Key | Sor_ID

AAA         | 100

BBB         | 200

Table 2
-----
Foreign Key | Sor_ID

AAA         | NULL

BBB         | NULL

---

create or replace
    Procedure UPDDATE_SORID_2 
IS
    s_id VARCHAR2(256 byte);

    CURSOR C1 IS
    SELECT A.SOR_INSTRMNT_ID
    FROM TEST_TABLE B,TEMP_SOR_ID A
    where A.INSTRMNT_KEY=B.INSTRMNT_KEY;
BEGIN

    open c1;
    loop
    fetch c1 into s_id;

    update TEST_TABLE set SOR_INSTRMNT_ID=S_ID; 

    commit;
    end LOOP;
    close c1;

EXCEPTION
    WHEN OTHERS THEN
    RAISE_APPLICATION_ERROR(-20001,'An error was encountered - '
                                    ||SQLCODE||' -ERROR'||SQLERRM);
end;

This procedure returns nothing updated even after hours of running it. Kindly suggest

Answer 1

You do not need cursors to do this.

If you have a foreign key relationship between the tables you can update on a key-preserved view of the two tables joined.

The general pattern would be:

Update (
  select parent_table.key   parent_key,
         child_table.key    child_key,
         parent_table.value parent_value,
         child_table.value  child_value
  from   parent_table
  join   child_table  on child_table.key = parent_table.key)
set
  child_value = parent_value;

This will be faster and more robust than a PL/SQL cursor-based method.

Incidentally, you can also delete child records using a similar technique of deleting against a key-preserved view.

Of course this does not answer the question of why you'd want to place a parent attribute in a child table.

Answer 2

I noticed a couple of problems with your procedure.

1) It runs forever because there is no EXIT from your loop.
2) Your update statement updates the whole table every time because you are not using a WHERE clause.

I recommend you alter as follows:

CREATE OR REPLACE PROCEDURE upddate_sorid_2
IS
    s_id VARCHAR2(256 byte);
    s_instrmnt_key VARCHAR2(256 byte);

    CURSOR c1 IS
    SELECT a.sor_instrmnt_id, a.instrmnt_key
    FROM test_table b,temp_sor_id a
    WHERE a.instrmnt_key = b.instrmnt_key;
BEGIN

    OPEN c1;
    LOOP
    FETCH c1 INTO s_id, s_instrmnt_key;

    EXIT WHEN c1%NOTFOUND;

    UPDATE test_table
    SET sor_instrmnt_id = s_id
    WHERE INSTRMNT_KEY = s_instrmnt_key; 

    END LOOP;

    CLOSE c1;

    COMMIT;

EXCEPTION
    WHEN OTHERS THEN
    RAISE_APPLICATION_ERROR(-20001,'An error was encountered - '
                                    ||SQLCODE||' -ERROR'||SQLERRM);
end;